From fellow Blender users here, I learned how to animate the drawing of a line in 3D space (I’ll use it for a video about charts and graphs). This lets me draw the line, over time, by using a small cylinder that has an Array modifier and a Curve modifier.
The Array mod lets me cap both ends of the line. The diameter of the cylinder, and the cap objects, is what sets the line’s thickness. It’s really a 3D tube that stretches to cover a spline (the Array mod’s “Fixed Count” property increases over time and the Merge box is checked).
It’s very powerful, easy to set up, but sometimes, the line gets thin, as in this example. The first sharp turn that the line makes is also a spot where the line gets thinner. Why? What should I do to avoid this? I’m looking for the simplest, fastest way to crank out these line-being-drawn animations without a lot of tweaking, I hope.
PROOF THAT ARROW TIP WORKS on animated drawing of a line.blend (641 KB)
Attachments
OK - three ways of doing it - the first is your method of using a shape with a Array and Curve Mod, I see the problem!
Second uses a Curve with a circle as the Bevel Object - converted to a curve using ALT+C => “Curve from Mesh”. Bevel objects MUST be curves.
Third uses a Curve with a plane as the Bevel Object - converted to a Curve. You animate the line progressing by keyframing the Bevel Start and End Offsets. The Arrows have curve modifiers and I then move them along the deformation axis to get them at the end of the “drawn” line.
Note! The Bevel Resolution is Spline - that way when you animate the Bevel End and the Arrow, they move together.
I don’t know if this looks better - the reason for the very slightly rounded corner is that I have a very tight radius (0) at the corner, it may be better to open this very slightly… I scaled the curve vertex to 0 to get the tight corner
Let me know if this looks better for you. The animation in this case is very smooth - you are not adding little bits at a time as you are with the Array thing.
Cheers, Clock.
Here’s a video of the technique: :eek:
Clock, thanks for taking a stab at this! I am not sure I’m following you correctly because, when I try “The Arrows have curve modifiers and I then move them along the deformation axis to get them at the end of the “drawn” line,” I get arrow heads that are distorted and flung out into 3D space far from the start or end point of the line.
I tried putting a Follow Path constraint on an arrowhead, instead of a Curve modifier, which almost works, but the arrow doesn’t orient itself to point in the direction the line is drawing.
Its tip seems to wander and turn sideways as it approaches a corner. It’s tough to animate the “Offset” of this arrow’s constraint in sync with the Bevel End of the line. There’s always a gap, somewhere in the animation.
Would you be willing to attach a .blend, whether new or just a modification of the .blend I attached in the first post?
I think I found a simple solution. Only experience will discover if I’m right, I think, but here goes:
I went into Edit mode on the path (that the animated line follows), selected the problem corner, and changed the Handle type to “Free” (I don’t know what it was before). That seemed to fix it, so I played around with the spline, adding and moving some more points. I selected all and clicked “Free” and, so far, the line diameter looks consistent.
I think I consider this prob solved.
Clockmender, thanks again for your help.
I’ll post the file later - I am busy until this evening, it may be useful to you.
Cheers, Clock.
